Remote sensing catheter system and methods

ABSTRACT

A remote sensing catheter system including an injection catheter and a collection catheter. In one method of use, an external sensor of the system determines the timing of operation of the collection catheter. In another method of use, a sensor determines the volume of medium in the injection.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. application Ser.No. 12/228,534, filed Aug. 12, 2008; which application is incorporatedherein by reference.

FIELD OF THE TECHNOLOGY

The present disclosure relates generally to devices and systems for usein the medical field, and various methods associated with such devicesand systems. More particularly, this disclosure relates to devices andsystems used in medical procedures involving the removal of a mediumfrom coronary circulation, and various methods associated therewith.

BACKGROUND

Coronary circulation is the circulation of blood in the vessels thatsupply blood to and from the heart muscle (the myocardium). The heart issupplied by the right and left coronary arteries and is drained mainlyby veins that empty into the coronary sinus.

Angiography is a medical imaging technique in which an X-ray orfluoroscopic image is taken to visualize the lumen of blood vessels andorgans of the body. To assist in the visualization process, a contrastmedia may be added to the blood.

One of the more common angiography procedures performed is thevisualization of the coronary arteries. Typically in this procedure, acatheter is used to administer the contrast media into one of the twomajor coronary arteries. X-ray images of the contrast media within theblood allow visualization of the size, anatomy, and patency of thearterial vessels.

Contrast media, however, can have significant health risks if permittedto flow systemically to the patient's organs. For example, renaldysfunction or failure may occur from such systemic delivery of contrastmedia. Such dysfunction or failure is referred to as “contrast-inducednephropathy” or CIN.

Systems and methods have been developed for the removal of contrastmedia and other mediums from the coronary circulation. For example, insome removal methods, a removal catheter is positioned to collect mediumas it exits the coronary circulation. In general, conventional systemsused to collect and remove medium from the coronary circulation, and theassociated conventional methods, can be improved.

SUMMARY

The present disclosure relates to a catheter system used in removing amedium from coronary circulation. In one aspect, the catheter systemfunctions to determine the timing of removal, and is based upon a starttime and a volume of an injection. In another aspect, the cathetersystem employs the use of at least one external sensor.

A variety of examples of desirable product features or methods are setforth in part in the description that follows, and in part will beapparent from the description, or may be learned by practicing variousaspects of the disclosure. The aspects of the disclosure may relate toindividual features as well as combinations of features, includingcombinations of features disclosed in separate embodiments. It is to beunderstood that both the foregoing general description and the followingdetailed description are explanatory only, and are not restrictive ofthe claimed invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of one embodiment of a sensingcatheter system, in accordance with the principles disclosed;

FIG. 2 is a one time line illustrating operation of the sensing cathetersystem of FIG. 1;

FIG. 3 is a another time line illustrating operation of the sensingcatheter system of FIG. 1;

FIG. 4 is a schematic representation of another embodiment of a sensingcatheter system, in accordance with the principles disclosed; and

FIG. 5 is an enlarged view of a collection sensor of the sensingcatheter system of FIG. 4.

DETAILED DESCRIPTION

Reference will now be made in detail to exemplary aspects of the presentdisclosure that are illustrated in the accompanying drawings. Whereverpossible, the same reference numbers will be used throughout thedrawings to refer to the same or like parts.

Contrast media is used to visualize the coronary vasculature as part ofcoronary diagnostic and therapeutic interventional procedures. Thecontrast media is toxic to the kidneys and may cause kidney impairment(contrast induced nephropathy), especially in patients with pre-existingkidney disease. Accordingly, contrast removal devices and proceduresincluding catheters for the collection and removal of contrast have beendeveloped. The procedures include inserting the catheter into thecoronary sinus (the main vein draining the heart). As the injectedcontrast media passes through the heart and arrives in the coronarysinus, a negative pressure is applied to the catheter and the contrastmixed with blood is removed from the body. Continuous collection orremoval of fluid from the coronary sinus can cause excessive blood loss.Therefore, timing of the removal is critical.

The present system and method relate to the timing of contrast removalfrom a vessel, such as the coronary sinus. In determining the mosteffective time for removal of contrast media from the coronary sinus,several events and/or factors are considered.

One factor is the transit time through the myocardium, from coronaryartery to coronary sinus. Transit time has been studied in patients withnormal and diseased coronary arteries. In the study, a marker solutionwas injected into the coronary artery; the arrival of the marker as wellas the washout of the marker through the coronary sinus was monitored.The results of this study demonstrate that the transit time isrelatively consistent for patients with normal coronary arteries. Inparticular, the marker arrived in the coronary sinus within two secondsafter the start of a coronary arterial injection, and washed through thecoronary sinus within an average of seven to eight seconds. Patientswith obstructed coronary arteries exhibited similar transit timeprofiles, only with a slightly lengthened washout time. Other publishedstudies as well as direct observations, show the transit time forcontrast injected in the coronary arteries to arrive in the coronarysinus is within 4 to seconds. The longer transit time for contrast maybe due to its increased viscosity. The present method and systemutilizes this information to improve upon conventional methods ofremoving a medium from the coronary sinus.

Referring now to FIG. 1, a schematic representation of a remote sensingcatheter system 10 for removing a medium from a patients' coronarycirculation system is illustrated. It is to be understood that “medium”includes, for example, both contrast media and other non-contrast media,such as detection agents (e.g., saline). The system 10 generallyincludes an injection catheter 12, a collection catheter 14, and avacuum or aspiration unit 16 that is in fluid communication with thecollection catheter 14.

The system 10 further includes an injection sensor 18 and an interfaceunit 20. The interface unit 20 is electrically connected to both of theinjection sensor 18 and the aspiration unit 16. During use, theinterface unit 20 controls the operation of the collection catheter 14.What is meant by ‘controls the “operation” of collection catheter’ isthat the interface unit 20 controls the activation and deactivation ofthe aspiration unit 16, which is in fluid communication with thecollection catheter 14.

In some removal devices, a sensor is incorporated into a removalcatheter and positioned internal to the coronary circulation system ofthe patient. The sensor is used to detect the arrival of contrast in acoronary vessel. Such internal sensors add significant complexity andcost into the design and manufacturing of the removal catheter. Thepresent system provides a less complex and less costly design than thatof systems having sensors placed within a patient's body during use. Inparticular, the injection sensor 18 of the present system 10 is remote,or located external to the patients' body during use of the system. Inthe illustrated embodiment, the injection sensor 18 is located betweenan injection syringe 22 and the injection catheter 12.

Referring still to FIG. 1, during use of the system 10, a distal end 24of the injection catheter 12 is positioned within the patient's coronaryartery. A distal end 26 of the collection catheter 14 is positionedwithin the patients' coronary sinus. In one method, the injection sensor18 is then utilized to activation or start the removal and/or collectionof a medium that has been injected into the patient's coronary arterythrough the injection catheter 12. Preferably, the removal starts at thetime when the medium arrives in the coronary sinus to maximize theremoval of the medium and minimize the removal of blood.

In particular, in the one method, the syringe 22 is used to inject themedium into the injection catheter 12. The injection of the medium isdetected in the injection catheter 12 by way of the injection sensor 18prior to the medium reaching the patient's coronary artery. The sensor18 can include a pressure sensor, flow sensor, impedance sensor, orother sensor that detects or measures a specific parameter of aninjection, or of the medium in the injection.

The sensor 18 establishes a start time of the injection. Operation ofthe collection catheter is then automatically initiated at apredetermined time after the start time of the injection. What is meantby “automatically” is that the operation is initiated by way of theinterface unit 20, as opposed to manually initiating operation (i.e.,manually activating the aspiration unit 16 and/or interface unit 20).The predetermined time after the start time of the injection typicallyincludes a delay to account for the transit time of the medium so thatoperation of the collection catheter coincides with the arrival of themedium in the coronary sinus. Referring to FIGS. 2 and 3, in one method,the predetermined time after the start time (labeled ActivationInterval) is about 2 to 6 seconds after the start time. In anothermethod, the predetermined time is 4 to 6 seconds after the start time.

In general, the remote sensing catheter system 10 starts or initiatesremoval of a medium based on the timing from a coronary arterialinjection. In addition to determining the timing for removal, thepresent system 10 can be used to determine whether or not the coronaryarterial injection is of a significant amount to warrant activation ofthe system.

In particular, physicians commonly introduce a small dosage of medium(often referred to as a “puff”) into the coronary artery for evaluationpurposes. The small puffs are sometimes introduced prior to asignificant injection amount, and are sometimes introduced after asignificant injection amount to evaluate the ongoing procedure.Collecting fluid from the coronary sinus after the injection of a puffis typically not recommended as more blood than medium is removed, whichcan lead to excessive blood loss depending upon the number of puffsemployed during the procedure.

The present system 10 can be used to determine whether the injection isa puff of medium or a significant amount of medium that warrantsremoval. In particular, the injection sensor 18 can be used to determinethe volume of medium in the injection. In one method, the interface unit20 initiates operation of the collection catheter 14 only when thevolume of medium in the injection is greater than a predeterminedamount. Smaller volumes of medium (puffs) are ignored and operation ofthe collection catheter is not initiated.

In one embodiment, the determination of the volume of medium in theinjection is based upon the duration of the injection. If the injectionlasts longer than a predetermined duration parameter, then a significantinjection amount is declared and operation of the collection catheter isinitiated at the predetermined time. Referring to FIGS. 2 and 3, theduration of injection that defines a significant injection amount isdefined by an injection duration that is greater than 1.5 seconds. Ascan be understood, the duration of the injection can end prior toinitiating operation of the collection catheter (FIG. 2) or end afterinitiating operation of the collection catheter (FIG. 3).

The injection sensor 18 of the present system 10 can further be used todetermine the timing of ceasing operation of the collection catheter 14.In such a method, the sensor 18 establishes an end time of theinjection, as well as the start time. Operation of the collectioncatheter is then automatically ceased a predetermined time after the endtime of the injection. What is meant by “automatically” is that theoperation is ceased by way of the interface unit 20, as opposed tomanually ceasing operation (i.e., manually deactivating the aspirationunit 16 and/or interface unit 20). Referring to FIGS. 2 and 3, in onemethod, the predetermined time after the end time (labeled DeactivationInterval) is about 4 to 10 seconds after the end time. Accordingly andin one method, operation of the collection catheter is initiated 2-6seconds after the start time of the injection and ceases 4 to 10 secondsafter the end time of the injection; the duration of operation of thecollection catheter typically being between 4 to 6 seconds.

In an alternative embodiment, the timing of ceasing operation of thecollection catheter 14 can be determined by use of a sensor. Referringnow to FIG. 4, the remote sensing catheter system 10 includes acollection sensor 28 that can be used to cease operation of thecollection catheter 14 after a desired majority of the medium has beenremoved from the coronary circulation. The interface unit 20 iselectrically connected to the collection sensor 28 as well as theinjection sensor 18 and the aspiration unit 16. The collection sensor 28is remote, or located external to the patients' body during use of thesystem 10. The external collection sensor provides a less complex andless costly design than that of systems having internal sensors placedwithin a patient's body during use. In the illustrated embodiment, thecollection sensor 28 is located between the collection catheter 14 andthe aspiration unit 16.

The collection sensor 28 detects or senses the presence and/or absenceof medium in the collection catheter 14. The sensor 28 can include animpedance sensor. Referring to FIGS. 4 and 5, in one embodiment, thesensor 28 includes an electrode array (e.g., x1, x2, x3) located withina disposal hub assembly 30 connected between a proximal end 32 of thecollection catheter 14 and connection tubing 34 of the aspiration unit16. Optical sensors, chemical sensors, density sensors, or other sensorsthat detect or measure a specific parameter of an injection or medium inthe injection can also be used. In use, when the absence, for example,of the medium in the collection catheter 14 is detected, operation ofthe collection catheter is automatically ceased.

Still referring to FIG. 4, it is to be understood that alternativesystems may include only the external collection sensor 28 (no injectionsensor 18). In such a system, the physician would manually actuateoperation of the collection catheter 14 a period of time, e.g., 2 to 3seconds, after starting the injection. Likewise and referring to FIG. 1,in a system including only an external injection sensor, a physician canalso manually cease operation of the collection catheter 14 a period oftime after the end of the injection.

The above specification provides a complete description of the presentinvention. Since many embodiments of the invention can be made withoutdeparting from the spirit and scope of the invention, certain aspects ofthe invention reside in the claims hereinafter appended.

1. A method of collecting a medium from a coronary sinus using acatheter system, the method comprising the steps of: a) providing acatheter system including a collection catheter; b) positioning a distalend of the collection catheter within the patient's coronary sinus; c)detecting an injection of the medium in the catheter system, including:i) establishing a start time of the injection; and ii) determining thevolume of medium in the injection; and d) initiating operation of thecollection catheter a predetermined time after the start time of theinjection, wherein the step of initiating operation occurs only when thevolume of medium in the injection is greater than a predeterminedamount.
 2. The method of claim 1, further including providing aninjection sensor that detects the injection of the medium.
 3. The methodof claim 2, wherein the injection sensor is located outside thepatient's body during use.
 4. The method of claim 2, further includingproviding an interface unit electrically connected to both the injectionsensor and an aspiration unit, the aspiration unit being in fluidcommunication with the collection catheter, the interface unitcontrolling the initiation of operation of the collection catheter. 5.The method of claim 1, wherein the predetermined time after the starttime of the injection is about 2 to 6 seconds.
 6. The method of claim 1,wherein the predetermined time after the start time of the injection isabout 4 to 6 seconds.
 7. The method of claim 1, wherein the step ofdetermining the volume of medium in the injection is based upon theduration of the injection.
 8. The method of claim 7, wherein the step ofinitiating operation occurs only when the duration of the injection isgreater than 1.5 seconds.
 9. The method of claim 1, wherein the step ofdetecting the injection occurs prior to the medium reaching thepatient's coronary artery.
 10. The method of claim 2, wherein theinjection sensor is a pressure sensor.
 11. The method of claim 1,further including establishing an end time of the injection, and ceasingoperation of the collection catheter a predetermined time after the endtime of the injection.
 12. The method of claim 11, wherein thepredetermined time after the end time of the injection is about 4 to 10seconds after the end time.
 13. The method of claim 1, further includingproviding a collection sensor that detects the absence of the medium inthe collection catheter, and ceasing operation of the collectioncatheter upon detecting the absence of the medium in the collectioncatheter.
 14. The method of claim 13, wherein the collection sensor isan impedance sensor.
 15. The method of claim 13, further includingproviding an interface unit electrically connected to both thecollection sensor and an aspiration unit, the aspiration unit being influid communication with the collection catheter, the interface unitcontrolling the cessation of operation of the collection catheter. 16.The method of claim 13, wherein the collection sensor is located outsidethe patient's body during use.
 17. The method of claim 1, wherein thestep of detecting the injection of the medium includes detecting theinjection of a contrast media.
 18. A method of collecting a medium froma coronary sinus using a catheter system, the method comprising thesteps of: a) providing a catheter system including a collectioncatheter, the collection catheter including a sensor, the sensor beinglocated outside a patient's body during use; b) positioning a distal endof the collection catheter within the patient's coronary sinus; c)initiating operation of the collection catheter to remove the mediumfrom the patient's coronary sinus; and d) ceasing operation of thecollection catheter when the sensor detects the absence of the medium inthe collection catheter.
 19. A method of removing a medium from acoronary sinus, the method comprising the steps of: a) providing acatheter system including: i) an injection senor, the injection sensorbeing external to a patient's body during use of the system; ii) acollection catheter and a collection sensor, the collection sensor beingexternal to the patient's body during use of the system; iii) anaspiration unit in fluid communication with the collection catheter; andiv) an interface unit electrically connected to each of the injectionsensor, the collection sensor, and the aspiration unit, the interfaceunit controlling the operation of the collection catheter; b)positioning a distal end of the collection catheter within the patient'scoronary sinus; c) detecting the injection of a medium in the cathetersystem with the injection sensor, prior to the medium reaching thepatient's coronary artery, the step of detecting including: i)establishing a start time of the injection; and ii) monitoring theinjection duration; d) automatically initiating operation of thecollection catheter a predetermined time after the start time of theinjection, wherein the step of initiating operation occurs only when theinjection duration is greater than a predetermined duration parameter;e) after initiating operation of the collection catheter, monitoring thecollection sensor for the presence of the medium in the collectioncatheter; and e) automatically ceasing operation of the collectioncatheter after a desired majority of the medium has been removed fromthe patient's coronary sinus.
 20. The method of claim 19, wherein theinjection sensor is a pressure sensor.
 21. The method of claim 19,wherein the collection sensor is an impedance sensor.
 22. The method ofclaim 19, wherein the predetermined time after the start time of theinjection is about 4 to 6 seconds.
 23. The method of claim 22, whereinthe predetermined duration parameter is 1.5 seconds.
 24. The method ofclaim 19, wherein the step of detecting the injection of the mediumincludes detecting the injection of a contrast media.
 25. The method ofclaim 1, wherein the step of providing the catheter system includesproviding the catheter system including an injection catheter, themethod further including positioning a distal end of the injectioncatheter within a patient's coronary artery, and detecting the injectionof the medium in the injection catheter of the catheter system.
 26. Themethod of claim 19, wherein the step of providing the catheter systemincludes providing the catheter system including an injection catheter,the method further including positioning a distal end of the injectioncatheter within a patient's coronary artery, and detecting the injectionof the medium in the injection catheter of the catheter system.